Process of and apparatus for cracking oil



p 1933- G. EGLOFF ,927, 59

PROCESS OF AND APPARATUS FOR CRACKING OIL Original Filed Dec. 50, 1925 Patented Sept. 19, 1933 UNITED STATES PATENT OFFICE PROCESS OF AND APPARATUS FOR CRACKING OIL Application December 30, 1925, Serial No. 78,302 Renewed June 4, 1923 7 Claims. (Cl. 19648) This invention relates to improvements in process of and apparatus for cracking oil and refers more particularly to that type of process and apparatus in which the oil is initially heated in a coil, then passed to an expansion chamber, the vapors removed therefrom and subjected to reflux condensing action, and the reflux condensate, either alone, or mixed with the raw oil that is introduced directly into the reflux condenser and returned to the heating coil for further treatment.

In a process of this character difficulty is experienced in stripping the charging stock, including the reflux condensate, of all'its gasoline before it enters the heating coil. In some cases as high as ten or more per cent of gasoline is contained in such charging stock, with the resuit that the gasoline which is already sufficiently cracked may be injured by further cracking. Moreover the capacity of the plant is cut down and heat units wasted in unnecessarily heating up the gasoline. The object of the present invention is to avoid this by stripping the charging stock of its gasoline as far as possible before it enters the heating coil.

The invention will be understood from the accompanying drawing, in which the single figure is a somewhat diagrammatic view partly in side elevation and partly in vertical section, of an apparatus suitable for carrying out the present invention.

Referring to the drawing, 1 designates the furnace in which is mounted coil 2 connected by feed line 3 to raw oil charging pump 4 leading to any suitable source of raw oil supply, say, for example, fuel oil. The delivery side of the coil 2 is connected by transfer line 5, controlled by throttle valvev 6 to an expansion chamber 7, which may be insulated or may be independently heated. It is provided with a residue draw-off 8 controlled by throttle valve 9 and vapor pipe 10 controlled by throttle valve 11, and leading to the side of a dephlegmator 12. This dephlegmator 12 is provided at its'upper" end with a vapor outlet pipe 13 controlled by throttle valve 14, which pipe 13 leads to condenser coil 15, and thence through line 16 having throttle valve 17 to receiver 18. Receiver 18 is provided with a gas outlet pipe 19 controlled by throttle valve 20 and liquid draw-off pipe 21 controlled by valve 22. The reflux condensate is drawn out of the dephlegmator through the reflux pipe 23, to which is connected a branch line 24, in which 'line is inserted a hot oil pump 25, leading to the main feed line 3. The raw oil may be in whole or in part first delivered to the dephlegmator and mixed with the reflux condensate by means of the pipe 26 having throttle valve 27 and connected with raw oil pump. A valve 28 is interposed in the line 3, so by controlling the valves 27 and 28 all or part of the raw oil may be fed either to the dephlegmator before entering the tubes or directly to the tubes.

As a feature of the invention I provide means for heating the lower part of the dephlegmator so as to insure stripping the gasoline out of the descending raw oil and reflux condensate in the event any rawoil is introduced directly to the dephlegmator, otherwise only from the reflux. To this end the pipe 23 extends, as shown, some distanceinto the dephlegmator and is provided with a spaced cap member 29. In the lower end of the dephlegmator is a so-called reboiler coil 30, one end of which is open into the dephlegmator as shown at 31 and the other end of which connects to pipe 32, which pipe 32 in turn connects to a coil 33 mounted in the furnace 1 as shown. The other end of the coil 33 is connected by pipe 34 to the lower part of the dephlegmator 12. In this pipe 34 is interposed a hot oil pump 80 35 with suitable throttle control valves 36. The arrangement is such that a regulated quantity of the reflux condensate, ormixture or reflux condensate and hot oil can be continuously circulated through the reboiler coil 30, thus maintaining the lower part of the dephlegmator at a sufiiciently high temperature to insure vaporizing out of the descending liquids whatever gasoline is therein contained. There is likely to be always a trace of gasoline, contained in the charging stock and reflux, or the reflux as it passes through the heating coil, but the present invention strips it of substantially all of the gasoline.

The. process may be operated as follows: The

raw oil, say, for example, fuel oil, is passed to the heating coil 2 where it is heated to a trans fer temperature of, say, 850 deg. F., with a pressure on the heating coil and on the entire system of 300 pounds. More or less of the raw oil is preferably fed up through the line 26 and mingled with the reflux condensate and as this charging stock descends, meets the hot ascending vapors. By passing the hot-oil through the reboiler coil in the manner heretofore stated; the temperature of the lower part of the dephlegmator will be maintained sufficiently high to distill out the gasoline contained therein.

I claim as my invention: no

1. A method for dephlegmating hydrocarbon III oil vapors evolved from hydrocarbon oils which have been subjected to cracking conditions of temperature and pressure, which comprises introducing the vapors to a'dephlegmating zone, collecting a body of reflux condensate separated from the vapors in said dephlegmating zone, continuously removing a portion of such body of reflux condensate from the dephlegmating zone, elevating the temperature of the portion removed from said reflux condensing zone above the temperature of said body of reflux condensate collecting in the dephlegmating zone and thereafter passing such reflux condensate for a substantial distance through a closed conduit positioned in the collected body of reflux condensate in said dephlegmating zone thereafter admitting said portion to said body and taking off uncondensed vapors from said dephlegmating zone, and maintaining a superatmospheric pressure on the vapors undergoing treatment in the dephlegmating zone. i

2. A process for treating hydrocarbon oil, comprising maintaining a body of oil under cracking conditions of temperature and pressure, introducing vapors evolved from the oil to a dephlegmating zone, collecting [in said dephlegmating zone a'substantial body of reflux condensate, continuously removing reflux condensate from said body, to be subsequently united with the body of oil maintained under cracking conditions of temperature and pressure, removing a further portion of reflux condensate from said dephlegmating zone, elevating thetemperature of said further portion of refiuxcondensate above the temperature of the body of reflux condensate collecting in said dephelgmating zone, returning such further portion of the reflux condensate, while at said elevated temperature, to the dephelgmating zone thence causing it to initially flow in heat interchange relation but out'of contact with said body of collected reflux condensate, and thereafter permitting said portion to again commingle with the reflux condensate in said body.

3. A process for treating hydrocarbon oil, comprising maintaining a body of oil under cracking conditions of temperature and pressure, introducing vapors evolved from the oil to a dephlegmating zone, collecting in said dephlegmating zone a substantial body of reflux condensate, continuously removing reflux condensate frbm said body, to be subsequently united with the body of oil maintained under cracking conditions of temperature and pressure, removing a further portion of reflux condensate from said dephlegmating zone, elevating the temperature of said further portion of reflux. condensate above the temperature of the body of reflux condensate collecting in said dephlegmating zone in returning such further portion of the reflux condensate, while at said elevated temperature, to the dephlegmating zone, initially passing such further portion of the reflux condensate in heat interchange relationship with the body of reflux condensate collected in said dephlegmating zone and thereafter introducing such further portion of the reflux condensate into said body of reflux condensate.

4. In a dephlegmator, the improvement which comprises a coil located inside the dephlegmator below the normal level of reflux condensate therein, means for withdrawing reflux from said dephlegmator, means for heating said reflux and means for returning said heated reflux to said coil, said coil having an open end adapted to discharge the heated reflux into the body of reflux in said dephlegmator.

5. A hydrocarbon oil cracking process which comprises subjecting charging oil to cracking conditions of temperature and pressure in a cracking zone, passing resultant vapors to a dephelegmating zone and condensing heavier fractions of the vapors therein as reflux condensate, collecting resultant reflux condensate in a pool in said dephlegmating zone, continuously removing reflux condensate from said pool and heating at least a portion thereof independently of said charging oil to above the temperature of said pool, passing the thus heated reflux condensate in indirect heat exchange relation with said pool, subsequently discharging the thus heated reflux condensate into said pool below the level thereof, and removing and condensing the vapors uncondensed in said dephlegmating zone.

6. A hydrocarbon oil cracking process which comprises subjecting charging oil to cracking conditions of temperature and pressure in a cracking zone, passingresultant vapors to a dephlegmating zone and condensing heavier frac tions of the vapors therein as reflux condensate, collecting resultant reflux condensate in a pool in said dephlegmating zone, continuously removing reflux condensate from said pool and heating at least a portion thereof independently of said charging oil to above the temperature of said pool, passing the thus heated reflux condensate in indirect heat exchange relation with said pool, subsequently discharging the thus heated reflux condensate into said pool below the level thereof, passing another portion of the removed reflux condensate to said cracking zone for further subjection to cracking conditions therein, and removing and condensing the vapors uncondensed in said dephlegmating zone.

7. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure in a cracking zone, passing resultant vapors to a dephlegmating zone, introducing fresh charging oil for the process into direct contact with the vapors in said dephlegmating zone and thereby condensing heavier fractions of the vapors as reflux condensate and forming a mixture of charging oil and reflux condensate, collecting said mixture in a pool in said dephlegmating zone, continuously withdrawing mixture from said pool and heating a portion thereof independently of the oil undergoing treatment in said cracking zone to above the-temperature of said pool, passing the thus heated portion in indirect heat exchange relation with said pool, subsequently discharging the thus heated portion of mixture into said pool below the level thereof, passing another portion of said mixture to said cracking zone for subjection to cracking conditions therein, and removing and condensing the vapors uncondensed in said dephlegmating zone.

GUSTAV EGLOFF. 

